Presently, for many end users in the packaging industry which employ substrate webs and rolls there is a problem in that the coefficient of friction (CoF) is often too high on both the front side and the back side of the substrate web to achieve proper processing on packaging lines and this is particularly problematic in the case of aluminum foils.
Typically, a low CoF is desirable and usually it is only necessary to provide a low CoF on one side of the aluminum foil. However, in a number of cases a low CoF on both sides of the web is required and thus a special coating needs to be applied to both sides.
U.S. Pat. No. 7,267,862 discloses the use of primary and secondary amides which interact favorably so as to control CoF in polyolefin and other films whilst US2008/0213522 is directed to a coated polymeric film for the use in a method of wrapping a ream of paper in a packaging film wherein the coating is used to control CoF. The polymeric film may be coated on both sides of the polymeric film.
Consequently, there is a requirement to provide a more efficient process that can modify the CoF on both the front side and the back side of a substrate web without the need to apply separate coatings thereon.